Telephone transmitter



May 17, 1927.

- c. R. MOORE TELEPHONE TRANSMITTER Filed Oct. 17, 1923 lm/e/rfar. I6/706. A2. Moo/g;

by my Patented May 17, 1927. I

UNITED STATES PATENT OFFICE.

CHARLES MOORE OF MAPLEWOOD, NEW ASSIGNOR TO WESTERN ELECTRIC COMPANY,INCORPORATED, OF NEW YORK, N. Y., A. CORPORATION OF NEW YORK.

TELEPHONE TRANSMITTER.

Application'flled October 17, 1923. 'Serial No. 669,028.

This invention relates to telephone transmitters tlieobject being toprovide an eflicient and inexpensive transmitter capable of, translatingsound-waves into electrical waves with minimum distortion.

In accordance with the general features of the invention there isprovided a structure. in which the moving parts are light but rigid andare so mounted that they will In respond accurately and readily to allvibrations within the normal sound range. More specifically theinvention comprises a light sound responsive diaphragm in the form of. adouble cone suitably supported to permit full translation of soundvibrations and cooperating with a microphonic button the closure ofwhich is a double cone diaphragm suitably mounted for damping and havingits apex in contact with the apex of the 20 sound responsive diaphragm.

In the drawings in which the invention is illustrated as applied toapush-pull transmitter, Fig. 1 represents a cross section of atransmitter embodying the invention.

Fig. 2 illustrates acircuit in'which the transmitter may be used.

As shown in the drawings, face plate 3 is provided with an internallythreaded flange at its periphery and oppositely projecting 3o concentricflanges 5 and 6. Flange 5 is provided with internalthreads to adjustablyreceive the microphone unit 7 and flange 6 is threaded for the usualmouth piece 8.. Between the flanges 5 and 6 are a series of perforations9 ;for the purpose of permittingthe sound waves to reach the diaphragmwhich preferably" consists of two conical-shaped discs 10 and 11 heldtogether at their peripheries by means of a number of thin paper or foilrings 12, loosely clamped between the face plate 3 and a rear plate 13having an externally threaded fiange33 at its periphery engagingthe-flange 4 on the face plate 3. The total thickness of the rings 12and 45 the discs 10 and 11 of the diaphragm should be somewhat less thanthe distance between the plates 3 and 13 at this point in order topermit substantiallyfree translation of the diaphragm. The rear plate 13has a thread- 50 ed flanged aperture 14 in which a microphone unit 15,similar to microphone unit 7, 1s adjustably secured. To the microphoneunit 7 is. attached a dome-shaped shell 16 for directing the sound wavesthrough the. 55 openings 9.

The microphone units 7 and are preferably of the barrier type in whichthe electrodes 17 and 18 forming the inner peripheral walls areseparated by a ring-shaped barrier 19 of insulating material. 4 The rearwalls 20 and electrodes 18 are suitably insulated from their cups 34.The inner surfaces of the rear walls 20 are also preferably given a coatof insulating compound to insulate them from the granular material.Conical closures are provided for the microphone units. Preferably eachclosure comprises two small cone-shaped discs 21 and 22 supportedagainst each other at their peripheries by means of paper or foil'rings23, a number of which are loosely disposed on each side of the diaphragmand supported in place by the clamping rings 24 which seat on an annularspacer member 35,'Which may be integral with the electrodes 17. Thethickness off-the spacer member 35 should be slightly greater than thetotal thickness of the rings 23 and .the discs 21 and 22. The apexes ofthe closures abut against apexes of the diaphragm and require no furtherconnection. The contact pressure between the diaphragm and the closuresmay be con trolled by adjusting the microphone units 7 and 15 in thelates 3 and 13. Lock nuts 25 may be provi ed to lock them in place afteradjustment. The electrodes 17 may be grounded to the case and the commonlead 26 connected thereto. An insulated terminal 27 may be-mounted on afaceplate 3 for connect'ing the electrodes 18in the microphone unit 7 toline 28"and similarly the electrode 18 of. the microphone 15 may beconnected to the line 29. o

The inner surfaces of the conical discs 22 and the walls 20 exposed tothe granular material are preferably given a coat of insulatingmaterial. The diaphragm members 10 and 11 and the closure members 21 and22' are preferab num or its a loys.

The circuits shown in -Fig. 2 is the usual push-pull. type 'circuitinwhich 1 is the transmitter, 26, 28 and 29, the connections thereto, 30the source of electric current, 31 the'induction' coil and 32 thereceiver.- What is claimed is: 1. In a transmitter, a sound responsivediaphragm, acarbon containing chamber and a conical-shaped closure ofsheet material for said chamber, theapex of said 010- v110 v made up ofthin sheet alumisure making contact with said diaphragm,

2. Ina transmitter, 'a conical diaphragm, a chamber for granularmaterial. a conical closure therefor, and means for supporting saiddiaphragm and said closure in contact at their apexes.

3. In a transmitter, a diaphragm havin a convex surface, a chamber forgranu ar material, a closure for said chamber having a convex surface,and means for supporting said diaphragm and said closure in contact atthe centers of their convex surfaces.

4. In a transmitter, a double conical diaphragm, a chamber for granularmaterial on each side of said diaphragm, a conical closure for eachchamber, and means for supporting said diaphragm and said closures incontact at their apexes.

5. In a transmitter, a hollow conical diaphragm, formed of two conicalmembers, a

chamber for granular material on each side of said diaphragm, a hollowclosure for each chamber formed of two conical members, and means forsupporting one member of each closure in contact with said diaphragm attheir apexes.

6. In a transmitter, a double conical diaphragm of thin sheet material,a casing therefor, a plurality of rings of thin material looselydisposed oneach side of said diaphragm between its periphery and saidcasmg, a pair of microphone units adjustably supported in said casing, adouble conical closure of thin material for each unit, a pluralit ofrings of thin material looselydispose on each side of each closure atits peripher and means supporting said closures an said diaphragm incontact at their apexes.

7. In a transmitter, a light substantially rigid double cone-shapeddiaphragm, supporting members permitting substantially free translationof said diaphragm in response to sound vibrations a microphone and, alight substantially rigid double conical closure for said unit, the apexof which contacts with said diaphragm, and supporting means permittingsubstantially free translation of said closure in response to the actionof said diaphragm.

8. In a transmitter, a light substantially rigiddouble cone-shapeddiaphragm, supporting means permitting substantially free translation ofsaid diaphragm in response to sound Waves, microphone units disposed oneach side of said diaphragm, a light substantiall rigid double conicalclosure for each unit, the apexes of said closures contacting with theapexes of said diaphra m, and means permitting substantially reetranslation of the closure in response to the vibrations transmittedfrom said diaphragm.

9. In atransmitter, a sound responsive diaphragm, a casing therefor, aplurality of loosely arranged thin rings in the casing on CHARLES R.MOORE.

